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author | David Rientjes <rientjes@google.com> | 2013-10-16 13:46:43 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-10-16 21:35:52 -0700 |
commit | 9c56751271e7a917783fb57ec49fe8382e0dc867 (patch) | |
tree | 7b3b11cc74ebbe7d6c30593e2803535ad4b23ccb /CREDITS | |
parent | 34ec4de42be5006abdd8d0c08b306ffaa64d0d5d (diff) | |
download | kernel_goldelico_gta04-9c56751271e7a917783fb57ec49fe8382e0dc867.zip kernel_goldelico_gta04-9c56751271e7a917783fb57ec49fe8382e0dc867.tar.gz kernel_goldelico_gta04-9c56751271e7a917783fb57ec49fe8382e0dc867.tar.bz2 |
mm, memcg: protect mem_cgroup_read_events for cpu hotplug
for_each_online_cpu() needs the protection of {get,put}_online_cpus() so
cpu_online_mask doesn't change during the iteration.
cpu_hotplug.lock is held while a cpu is going down, it's a coarse lock
that is used kernel-wide to synchronize cpu hotplug activity. Memcg has
a cpu hotplug notifier, called while there may not be any cpu hotplug
refcounts, which drains per-cpu event counts to memcg->nocpu_base.events
to maintain a cumulative event count as cpus disappear. Without
get_online_cpus() in mem_cgroup_read_events(), it's possible to account
for the event count on a dying cpu twice, and this value may be
significantly large.
In fact, all memcg->pcp_counter_lock use should be nested by
{get,put}_online_cpus().
This fixes that issue and ensures the reported statistics are not vastly
over-reported during cpu hotplug.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'CREDITS')
0 files changed, 0 insertions, 0 deletions